122 RECOGNITION OF FRIENDS 
friend from nest A. In the evening the former waa 
killed, the latter was quite at home. 
October 19.—I put one ina small bottle with a 
friend from nest A. They did not show any enmity. I 
then put in a stranger; and one of them immediately 
began to fight with her. 
October 24,—I again put into the nest a stranger 
and a friend. The former was attacked, but not the 
latter. The following day I found the former almost 
dead, while the friend was all right. 
October 31.—I again put a stranger and a friend into 
the nest. The former was at once attacked; in this 
ease the friend also was, for a moment, seized by the 
leg, but at once released again. On the following 
morning the stranger was dead, the friend was all 
right. 
November 7.—Again I putin a stranger and a friend. 
The former was soon attacked and eventually driven 
out; of the latter they did not seem to me to take any 
particular notice. I could see no signs of welcome, no 
gathering round a returned friend; but, on the other 
hand, she was not attacked. 
Again, I separated one of my colonies of Formica 
fusca into two halves on August 4, 1875, and kept 
them entirely apart. From time to time I put speci- 
mens from the one half back into the other. The de- 
tails of this experiment will be found in the Appendix. 
At first the friends were always amicably received, but 
after some months’ separation they were occasionally 
